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NASA report: Software, tight budget doomed Mars lander

Illustration of the Polar Lander with descent engines firing

In this story:

Software fix was easy, cheap

Microprobes were 'not ready for launch'

2001 Mars lander mission canceled

Conclusion: 'If not ready, do not launch'


March 28, 2000
Web posted at: 5:42 p.m. EST (2242 GMT)

WASHINGTON -- A software flaw probably caused the Mars Polar Lander to shut off its descent engines prematurely, sending it on a fatal plunge into the red planet, according to a report released Tuesday.

So goes the most likely scenario for the demise of the lander, according to Tom Young, a former Lockheed Martin executive who presented a NASA blue ribbon report on the fate of the $165 million spacecraft.


"Spurious signals were generated when the lander legs deployed during descent," Young said. "It gave a false indication that the lander (had) landed."

The malfunction would have happened when the lander was about 40 meters, or slightly more than 100 feet, above the surface. "It would have hit at 22 meters per second, or 50 miles per hour," he said.

If the lander had come that close to the red planet, "undoubtedly" this malfunction caused its destruction, Young told reporters. But no one could know for certain. The design of the lander prevented any communications as the spacecraft attempted to land.

Software fix was easy, cheap

Regardless of the cause, Young suggested, similar NASA missions should require more funding, better training and more computer program testing.

"There was inadequate software design and testing. The software should have been designed to prevent premature engine shutdown," he said. "In space, one strike and you're out."

There was a full-scale test of the suspect software before flight, but some touchdown sensors were incorrectly wired, Young said. After the wiring was corrected, the test was not repeated.

Had the defect been known, a software correction would have been simple and inexpensive, he said.

Microprobes were 'not ready for launch'

Kennedy Space Center technicians lower the Mars Polar Lander onto a workstand in this 1998 file photo

The spacecraft was to have landed near the planet's south pole to search for signs of water. Two small probes that ejected from the craft also disappeared. They were supposed to plunge to the martian surface and analyze subsurface soil samples.

"It is clear that the microprobes were not adequately tested and were not ready for launch," the Mars Program Independent Assessment Team report said.

The lander's companion spacecraft, the Mars Climate Orbiter, was destroyed in September in a mix-up over metric and English measurements.

Engineers failed to convert numbers in a navigational program, leading the spacecraft to pass too close to the planet. Presumably, it burned up in the martian atmosphere. The two spacecraft cost a total of $320 million.

2001 Mars lander mission canceled

Lockheed Martin technicians working on a 2001 Mars Lander mission discovered the computer error. "They came to the conclusion that spurious signals could be present and cause failure if not compensated for in the software," Young said.

Ed Weiler, NASA's associate administrator, told reporters that the agency had decided to cancel the planned Mars 2001 Lander mission, which would have deployed a spacecraft nearly identical to the Polar Lander along with a six-wheeled rover.

He said the mission failures were regrettable, but not entirely unexpected, after NASA, faced with shrinking budgets, adopted a policy of "faster, better, cheaper," almost a decade ago.

"We said up front that this will be painful. We will be taking risks. We will be pushing the limits. We may lose two out of every 10 missions," he said.

But Weiler defended NASA's Mars missions, saying most have been successful and that ones in recent decades have gone aloft at a fraction of the cost of their predecessors.

Young, a former executive with Lockheed Martin, a primary NASA contractor, said he did not see a conflict of interest in his leadership of the review panel.

Conclusion: 'If not ready, do not launch'

He likened the situation to being "a doctor and having a friend who's sick."

"The worst thing you can do is tell the friend they're really not sick," Young said.

The blue-ribbon panel suggested numerous ways for NASA to improve performance, including ensuring that future spacecraft can communicate with mission managers during landing. The doomed lander was designed to turn its radio antenna away from Earth temporarily during descent.

Other recommendations include increased involvement from senior managers and improved communications with contractors.

According to the report, "the final observation that needs to be made is: If not ready, do not launch."

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NASA Homepage
Young Report Summary
Mars Exploration
The Mars Society
Mars Polar Lander

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